Health Calculators Calculators
Five free tools for everyday health screening and planning — from body weight classification to daily hydration needs. Built for quick, private, on-device calculations.
Health calculators are most useful as a starting point for a conversation with a doctor or trainer, not a replacement for one. These five tools use formulas referenced from major health bodies like the WHO, CDC, and NIH, so the numbers you get are grounded in recognized standards.
Each calculator accepts both metric (kg, cm) and imperial (lbs, ft/in) units, so it doesn't matter which system you normally think in. None of them account for individual factors like medical conditions, medications, or body composition — the result is a general estimate, and the page for each calculator explains where that estimate tends to be less reliable.
❤️ All Health Calculators
🧭 Which Health Calculator Should You Use?
Checking your weight category
The BMI Calculator gives a quick screening classification using WHO standard ranges.
Planning weight loss or gain
The Calorie Calculator estimates your TDEE (daily energy burn) using the Mifflin-St Jeor formula.
Staying hydrated
The Water Intake Calculator adjusts your daily target for body weight, activity level, and climate.
Tracking a pregnancy
The Pregnancy Calculator estimates your due date and current trimester from your last period or conception date.
Fixing your sleep schedule
The Sleep Calculator finds ideal bed/wake times based on 90-minute sleep cycles.
❓ Frequently Asked Questions
❓ Can these calculators replace a doctor's advice?
No. These tools are for general screening and education only. For any medical decision, talk to a qualified healthcare professional.
❓ Is BMI accurate for athletes?
Not always — BMI can't distinguish muscle from fat, so athletes with high muscle mass often score as 'overweight' despite low body fat. See the BMI Calculator's guide for details.
❓ Where do the formulas come from?
Each calculator lists its references at the bottom of the page, including sources like WHO, CDC, and NIH.
❓ Do these calculators work in both kg/cm and lbs/ft?
Yes, every health calculator on this page has a unit toggle so you can enter measurements in either metric or imperial without converting them yourself.
❓ How often should I recheck these numbers?
It depends on the calculator — weight-based results like BMI or calorie needs are worth rechecking after a meaningful weight change, while the Pregnancy and Sleep calculators are designed to be used regularly as your dates or schedule change.